Conventional internal combustion engines, such as those used in motor vehicles, have long employed spark producing systems for initiating combustion of fuels within combustion cylinder chambers. Although "spark plug" type devices for initiating fuel combustion have gained almost universal use in the past, it has been known that these devices were not particularly efficient in maximizing fuel combustion, hence, additional fuel was required to achieve a desired level of power output; moreover, incomplete fuel combustion resulted in the production of air pollutants which had to be dealt with. In order to assure satisfactory operation, prior art spark plug devices have required that the spark discharge produced thereby communicate with a region within the combustion chamber where an optimum (stoichiometric) fuel-to-air mixture exists, since the resulting energy density of combustion from a stoichiometric region within the chamber is usually high enough to ensure that the remainder of the fuel achieves combustion. Inasmuch as the energy produced by the spark discharge is insufficient to induce combustion of fuel-to-air mixtures which are not stoichiometric, richer mixtures of fuel to air were required in the past in order to assure that the spark discharge reached a stoichiometric region within the combustion chamber. However, due to the limited volume within the chamber which might be reached by a spark discharge, stoichiometric values of fuel to air mixtures could not always be provided under cold starting, idling, or part load operating conditions.
Because of the problems discussed above related to the relatively low energy produced by spark discharge systems, numerous attempts have been made in the past to increase the energy delivered by the spark discharge, and various prior art spark plug improvements are alleged to yield a "hotter spark", but none of such prior art spark plug devices are in fact capable of delivering the level of power needed to produce relatively complete combustion of fuel to air mixtures which are less than stoichiometric.
Ignition devices for producing an ignition plasma, such as that disclosed in U.S. Pat. No. 3,842,818, have been devised in an effort to increase the level of energy delivered to the fuel to air mixture, but the energy levels achieved by these plasma producing devices have not been sufficient to initiate combustion in fuel-to-air mixtures which are relatively far from stoichiometric, and therefore achieved satisfactory results only when a stoichiometric region of such fuel-to-air mixture was in proximity to the ignition plasma.
Another prior art attempt at solving the problem involves providing a combustion chamber physically configured to produce stratification of the fuel-to-air therewithin, whereby the richer mixtures are produced mixtures in a region immediately adjacent a conventional spark discharge initiating device, thereby assuring that the initiating spark reaches a region of fuel-to-air mixture which is close to stoichiometric.